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This hot central star of about 100,000 K has now blown off its outer layers and is making the nebula fluoresce brightly from the emission of its intense ultraviolet radiation. [6] The 16th magnitude star is an A-type main-sequence star of type A2V, and is separated from the white dwarf by at least 1277 au . [ 7 ]
NGC 7027 has a rich and highly ionized spectrum caused by its hot central star. [7] The progenitor star of NGC 7027 is believed to have been about 3 to 4 times the mass of the Sun before the nebula was formed. [7] It is possible that the central white dwarf of NGC 7027 has an accretion disk that acts as a source of high temperatures. [24]
All planetary nebulae form at the end of the life of a star of intermediate mass, about 1-8 solar masses. It is expected that the Sun will form a planetary nebula at the end of its life cycle. [8] They are relatively short-lived phenomena, lasting perhaps a few tens of millennia, compared to considerably longer phases of stellar evolution. [9]
IC 11, Sh2-184, [3] Sharpless 184, [1] LBN 616, LBN 123.17-06.28, Pacman Nebula See also: Lists of nebulae NGC 281 , IC 11 or Sh2-184 is a bright emission nebula and part of an H II region in the northern constellation of Cassiopeia and is part of the Milky Way 's Perseus Spiral Arm .
N44 is classified as an emission nebula because it contains large regions of ionized hydrogen. However, the three strongest emission lines in the nebula are singly ionized oxygen atoms, which emit at an ultraviolet wavelength of 372.7 nm , doubly-ionized oxygen atoms, which emit at a blue-green wavelength of 500.7 nm, and neutral hydrogen atoms ...
The nebula was formed about 70,000 years ago by the star EZ Canis Majoris throwing off its outer hydrogen layers, revealing inner layers of heavier elements. [2] Fast stellar winds, blowing at 1,700 km/s (3.8 million mph) from this star, create the bubble-shaped nebula as they sweep up slower moving material from an earlier phase of the star's evolution.
NGC 7635, also known as the Bubble Nebula, Sharpless 162, or Caldwell 11, is an H II region [1] emission nebula in the constellation Cassiopeia. It lies close to the open cluster Messier 52 . The "bubble" is created by the stellar wind from a massive hot, 8.7 [ 1 ] magnitude young central star , SAO 20575 ( BD+60°2522 ). [ 7 ]
The nebula is known as S 142 in the 1959 Sharpless catalog (Sh2-142). [2] It is extremely difficult to observe visually, usually requiring very dark skies and an O-III filter. The NGC 7380 complex is located at a distance of approximately 8.5 kilolight-years from the Sun , in the Perseus Arm of the Milky Way .